1. Field of the Invention
The present invention relates to an apparatus for retaining an annular plate against the radial surface of a disk for retaining rotor blades.
2. Description of the Prior Art
Boltless rotor blade retainers have been developed to reduce problems related to localized stress concentration in a rotor disk rim and blade retainers, reduce installation time and complications, and weight. Furthermore, they require additional tools.
One type of design is known in French Patent 2,485,117. It employs an annular retaining plate that is retained against a radial disk surface. The disk includes an annular recess formed along the radial surface that is bounded by several walls of which one is constituted by one side of a radially outwardly extending flange. The plate includes an axially extending base that is adapted to slidably engage with a radially outer wall of the recess. The plate also includes a leg extending radially inward to engage with the recess. The apparatus further includes an annular retaining ring that is disposed in the recess of the disk and is shaped to receive a portion of the leg which is also disposed within the recess to secure the blade retainer to the disk.
In order to install the retaining plate, the split annular retaining ring is inserted into the disk recess and compressed radially inward into the recess using compression tools disposed along the peripheral ring wall. Compression occurs until the tools come to rest against the flange. Next the base and the leg are inserted into the recess until a portion of the arm abuts the side of the disk. An axial force is applied to the retaining plate in order to urge the base and the leg to deflect inwardly, clearing the radially inner wall. A clamping tool is used to accomplish the deflection. At this point, the compression tools that compressed the annular ring are released. The ring then expands radially outward and the axial force applied to the retaining plate is released. Thereupon, the plate leg comes to rest against the two walls bounding the lip of the annular ring.
Accordingly, the use of the plate retaining device of the said French patent 2,485,117 entails special tools including the compression and clamping tools to compress the retaining ring when assembling the plate.
The objective of the present invention is an apparatus that axially engages the retaining plate and permits simple installation.
Another object of the invention is to enable assembling the retaining plate onto the disk without special tools that compress the retaining ring and deflect the retaining plate.
Still another objective of the invention is an apparatus that axially retains the plate and enhances the disk service life.
The invention attains its objectives in that the plate leg and the retaining ring form annular and mutually facing bevels to compress the ring previously placed in the recess when the base was made to slide axially in the recess as the plate was assembled to the disk.
Preferably the following design steps also shall be observed:
the bevels slant by an angle between 10 and 60xc2x0 relative to the disk axis,
the lip is bounded by a surface radially resting on the leg end and by a radial surface resting on the leg""s side which faces the recess aperture, the radial surface leading to the retaining ring""s bevel,
the part of the leg received in the lip is fitted with notches,
the lip comprises protrusions which will be inserted into the leg""s notches,
The notch depth is larger than the protrusion height.
The last design step allows slipping a tool into the space subtended between the protrusion peaks and the notch bottoms for the purpose of compressing the retaining ring when the plate is disassembled during maintenance operations. However, no special tool is used when reassembling the plate.
The geometry of the notches and protrusions allows keeping the retaining ring irrotational relative to the plate. This plate is thereby fixed in position relative to the disk at the level of the blade roots. With regard to the French patent 2,485,117, the retaining ring is affixed to the disk at a recess in the flange bounding the recess. Accordingly, such a recess is not required in the present invention and thereby disk construction is simplified and disk service life is extended.